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Operation
6
SNVU583 – February 2018
Copyright © 2018, Texas Instruments Incorporated
LMR33630xRNXEVM User’s Guide
Figure 5. FRA Setup
2
Operation
Once the above connections are made and the appropriate jumpers are set, the EVM is ready for use. If
external control of the EN input is desired, remove the EN jumper, and apply the external signal to the EN
test point and GND. The PGOOD output is pulled up to VCC through a 20-k
Ω
resistor. In this way the
PGOOD signal swings from 0 V to about 5 V to indicate when the output voltage is either outside or inside
of the PGOOD window, respectively. If an external pullup and supply is desired for the PGOOD function,
remove the 20-k
Ω
resistor, and pull the PGOOD test point up to the desired voltage through an
appropriate resistance. See the
for more details.
The output voltage of the EVM can be selected, by the VOUT jumper, to either 3.3 V or 5 V. Other values
of output voltage can be programmed by changing the value of R
FBB
on the EVM. In addition the values of
the inductor and the output capacitance may also need to be changed. See the
for
more information.
The EVM has been designed for maximum flexibility regarding component selection. This allows the user
to place preferred components, such as the inductor and/or capacitors, on the board and test the
performance of the regulator. In this way the power supply system can be tested before committing the
design to production.
The EVM also has locations for the components of an EMI filter. Note that these components are not
included with the EVM. Suggested component values are found in
. To use the EMI filter, the input
voltage to the EVM should be routed as shown in
. Note that if a common-mode choke is used,
then the input and output grounds are not at the same potential.
